The invention relates to a remote control system and, more particularly, to a remote control system containing a transmitter having a current storage device and a transmit key. An operator actuates the transmitter for the transmission, when desired, of control signals fed from the current storage device. The remote control system includes a charge monitoring device for monitoring the charge state of the current storage device. The charge monitoring device has a charge-state indicator for generating a signal directed at the operator. The remote control system also contains a receptacle for inserting the transmitter and making contact between the transmitter and an element connected downstream of the receptacle.
A known remote control system with these features is described in German Patent Document DE 33 14 072 C2 and is provided, in particular, for the remote control of a lock system for the mechanical and electronic control of vehicle locks. Its hand-held transmitter has a separate charge monitoring device with indicator and also has power pick-up contacts for making electrical contact with the vehicle electrical system. The pick-up contacts, when plugging the transmitter into a specially provided receptacle inside the vehicle, e.g., on the ignition lock, are electrically connected to corresponding connection contacts of the receptacle. When making contact with the connection contacts in the receptacle or by pressing its transmit key, the transmitter is made to transmit a control signal via its signal output into the receptacle, which signal is evaluated by a receiving device.
The reference describes nothing further regarding the mode of operation of the charge-state indicator of the class-forming remote control system. However, it is customary that, when actuating the transmitter, the charge state indicator is activated if the charge state of the current storage device is still sufficient, and thus constitutes an active state monitoring facility.
A device for preventing unauthorized use of a vehicle is known from German Patent Document DE 30 43 627 C2 which also contains a transmitter for the wireless transmission of control signals and a separately provided transmitter receptacle in the passenger compartment of the vehicle. If the transmitter is inserted into this receptacle into which an optical cable leads, its transmit key can be automatically actuated by a cam arranged in the receptacle in the movement path of the transmit key so that a control signal is emitted by the transmitter and transmitted into and via the aforesaid optical cable. In the known device, this automatically emitted control merely serves for canceling or unlocking a lock provided for an element which is essential for the operation of the vehicle. The lock is controlled by output signals of a receiving device connected to the optical cable on the other side and tuned to the control signals of the transmitter.
The aforesaid simple mechanical forced triggering of a transmitter signal, by means of a cam, cannot be applied to a transmitter having a transmit key that is flush with the outer case of the transmitter itself when inactive and whose actuating device is at an angle to the direction in which the transmitter is inserted into the receptacle.
In the system mentioned above, the transmitter only optionally has a separate current storage device. In the publication DE 33 14 072 C2 mentioned above, no statement is given concerning a charge-state monitoring facility with indicator.
The transmitter, i.e. a hand-held transmitter, of a further known remote control system described in DE 34 46 245 A1 also contains a charge monitoring device for the charge state of its current storage device. The charge monitoring device is triggered in the event of the actuation of the transmitter and a subsequently internally detected low residual charge of the current storage device and generates a visual or audible warning signal directed at the operator. This system contains no vehicle-internal receptacle for the transmitter.
Battery testing devices are known, e.g. DE-Z mot Service-Magazin, issue 20, Sept. 14, 1990, page 157, which measure the charge state, e.g. of motor-vehicle lead accumulators, and also displays the charge state.
There is therefore needed a remote control system of the above-mentioned type having a device external to the transmitter device for testing the charge state of the current storage device and, if appropriate, generating a warning signal.
The need is met according to the present invention by a remote control system containing a transmitter having a current storage device and a transmit key. The transmitter is actuated by an operator for the transmission, when desired, of control signals fed from the current storage device. The remote control system includes a charge monitoring device for monitoring the charge state of the current storage device. The charge monitoring device has a charge-state indicator for generating a signal directed at the operator. The remote control system also contains a receptacle for inserting the transmitter and making contact between the transmitter and an element connected downstream of the receptacle. The charge monitoring device and the charge-state indicator are arranged outside the transmitter. The charge monitoring device is connected downstream of the receptacle. The charge state of the current storage device is monitored by the charge monitoring device with the transmitter inserted into the receptacle and actuated inside the latter. The charge-state indicator is activated at a charge state of the current storage device.
By assigning the charge monitoring device to an external receptacle for the transmitter of the remote control system, into which receptacle the transmitter can be inserted and in which contact is made with it either electrically or by means of a control signal, and by activating the associated visual and/or audible charge-state indicator when the transmitter is actuated inside the receptacle in the event of an insufficient charge state of the current storage device of the transmitter, a reliable monitoring of its capacity is obtained without having to provide in the transmitter itself a device which takes up installation space at least with respect to the charge-state indicator.
Furthermore, in this case, the functioning of the charge-state indicator is not dependent on the residual capacity of the current storage device but rather the warning indicator is fed from an external source.
A variant of the capacity or charge-state monitoring device uses the energy pick-up contacts, known per se, of the transmitter and the connection contacts, corresponding thereto, of the receptacle for making direct electrical contact between the transmitter or its current storage device and the charge monitoring device and for measuring voltage and/or power of the current storage device by means of the charge monitoring device. Here, it is not absolutely necessary to also actuate the transmitter. However, it may be equally appropriate to measure the state of the current storage device during an actuation of the transmitter, i.e. when under load.
A different variant uses an indirect detection, in that, contact is made between the transmitter and the charge monitoring device connected downstream of the receptacle only indirectly via the contactless transmission of the transmitter's control signals. Here, the intensity of the control signal emitted by the transmitter during its actuation in the receptacle is detected. If this intensity should undershoot a threshold value, it is concluded that failure of the current storage device or of its charge is imminent and a warning signal is generated.
In the intensity evaluation, the absolute value of the received signal intensity can be detected, for example, by measuring the voltage (in the case of infrared transmission the photoelectric voltage) generated by the reception in the receiver of the emitted control signal, and comparing it with a reference or threshold value. The charge-state indicator is switched on when this value is undershot.
In the present case, it is to be considered additionally that the transmitter is used generally at a relatively large distance from the corresponding receiver, for example, for the remote control of a vehicle lock or also of a different remote-controllable element. However, if the transmitter is used in the receptacle, wherein its output, for example an infrared transmitting diode, is located in essentially the direct vicinity of a receiver, there is consequently in principle--with a well-charged current storage device--an excess of intensity with respect to the other aforesaid applications.
In accordance with a further advantageous feature of the invention, a filter can therefore be installed, especially in view of the generally preferred infrared-light transmission of the control signals, in a manner known per se from German Patent Document DE 36 39 715 A1. The filter is installed between the transmitter signal output and the receiver, which slightly weakens the intensity of the control signals, which can still be received behind the filter, in comparison with the emitted intensity. As a result, the aforesaid intensity excess is in all cases partially reduced in a selected fashion. An equivalent design is of course also possible in principle, even when using other transmission media, for example radio or ultrasound.
The charge-state indicator can thus be activated when the transmitter is located in the receptacle and has also been actuated but, in spite of this, no signal could be detected by the receiver.
By selective selection of the filter effect or of the degree of filtering or damping, the desired warning threshold value or the reference intensity excess to be tested can be varied within wide limits.
The main advantage of such an arrangement consists in the fact that an actual threshold value evaluation is no longer required since it is simply concluded that discharging of the current storage device has occurred from the face that no signal is received despite transmitter actuation.
Other features relate to the triggering of a control signal emission of the transmitter which is inserted into the receptacle. Of course, it would in principle be possible to wait before the detection of the state to determine whether or when the operator of the transmitter manually activates it.
Preferred variants will then already automatically actuate the transmitter in a suitable manner when it is inserted into the receptacle or only after a timing interval following the plug-in process.
This is simplest with a transmitter whose transmit key can be actuated in a direction parallel to the plug-in direction and is located at the front in the plug-in direction because the key can then be pushed against a corresponding projection in the receptacle.
Of course, for the simultaneous charge-state monitoring by means of the signal intensity another device is necessary which detects the presence of the transmitter in the receptacle in case the charge of the current storage device should no longer be sufficient for the generation of an evaluatable signal.
This can also operate via the receiving contacts, known per se, of the receptacle.
However, in addition to or instead of the detection via the aforesaid receiving or connection contacts, a separate detection device can be provided. The separate detection device operates, for example, mechanically or electrically. Possible solutions are electromechanical keys which project into the receptacle and are actuated when the transmitter is plugged in, it being possible for an actuation tappet to be driving, for example, via an actuating element, which tappet itself acts on the transmit key of the transmitter.
Purely mechanical solutions, for example with a spring-loaded switching sensor and an actuation tappet connected mechanically thereto and acting on the transmit key of the transmitter are also possible for the combined detection of the presence of and forced triggering of a transmitter signal in the receptacle.
A further interesting variant is contactless, in particular inductive or capacitive, detection of the transmitter in the receptacle. In this way, on the one hand its presence can be detected and on the other hand, in a manner known per se from German Patent Document DE 35 01 482 A1, the transmitter can be made to emit automatically a control signal whose intensity can then be detected in the above-describe manner.
Finally, it is also to be noted that a photoelectric barrier can be used for detecting the presence of the transmitter in the receptacle.
In a motor vehicle-specific solution of the type mentioned above, in which an active sensor for presence detection is fed from the electrical system of the vehicle and is provided in the receptacle which will be located, for example, in the dashboard of the vehicle, it is of course advisable in view of the limited capacity of the vehicle battery not to switch on the respective sensor until the vehicle is unlocked. It is known that such unlocking can also be controlled by means of the remote control system transmitter in question.
With a transmitter which is combined in a known manner with a mechanical (ignition) key, the presence detection, the triggering of signals and the charge-state monitoring could be carried out as further variants in conjunction with and as a function of the key actuation of a cylinder lock serving as the receptacle.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.